Atticus and Alexandra had a major disagreement earlier (in Chapter 14) when they argued about whether Calpurnia would be remaining in the household. (Scout overheard only a part of the conversation and thought they were talking about getting rid of her!) Atticus won that argument.

In Chapter 16, Alexandra first admonished her brother for what she considered speaking a little too honestly in front of Calpurnia.

"Don't talk like that in front of them... Like that in front of Calpurnia. You said Braxton Underwood despises Negroes right in front of her."

When Atticus responded with, "'Everybody in Maycomb knows it,'" Alexandra complained that Calpurnia would spread the gossip all over the "'Quarters before sundown.'" Atticus defended the Negroes' right to speak their mind.

Their second disagreement was much shorter. After Atticus defended Mr. Cunningham after their altercation the night before, Scout took a different point of view:

"First day Walter comes back to school'll be his last," I affirmed.

Atticus firmly told Scout that:

"You will not touch him... I don't want either of you bearing a grudge about this thing..."

Atticus and Aunt Alexandra disagree over two major points throughout the book, but especially in chapter 16. These points are parenting children and race.

First, in parenting, Atticus allows his children to be children, but they are required to comply with a no-nonsense approach to respect. Alexandra wants them to understand their gentle-breeding. She wants the to believe they are better than other people just because they are Finches. This is part of Aunt Alexandra's plight to get Scout wearing dresses. Atticus believes all people are equal and deserve respect.

Second, Alexandra has an racist attitude towards black folks. This is shown by her adaptation to the fine ladies of Maycomb who you will later see call their black staff "darky", and she doesn't want the children anywhere around the trial. Atticus would like to mildly protect them from it, but in the coming chapters you'll see him give in to let them see the truth. Atticus doesn't shelter his children from the truth of the ugliness of society. Alexandra would like to do that.